The present invention relates generally to movement devices for agitating the contents of syringes and, more particularly, to syringes and injectors incorporating movement devices for agitating contrast agents disposed within the syringes.
Syringes which are prefilled with ultrasound contrast agents are clamped into injectors for injection. The syringes remain therein for several minutes to one or more hours. The duration of one or more injections, including the intervening periods between the injections, may last for more than 10 minutes Depending on the nature and composition of the contrast agent, dissociation commences at different times. During this period, the ultrasound contrast agent becomes dissociated and the phases are separated from one another. The ultrasound contrast agent as a whole is no longer homogeneous. In order to restore this homogeneity, the entire injector, including the syringe clamped therein, is moved manually. Movements of this nature are not reproducible, and sufficient homogenization is not ensured.
Ultrasound contrast agents are sensitive to transverse forces. Under excessively high forces, the particles are torn apart and destroyed. This impairs the quality of the ultrasound contrast agent. Thus, to maintain the suspension of particles in ultrasound contrast agents it is necessary to agitate the agents, but at the same time the particles must not be destroyed by the agitation.
Ultrasound contrast agents are generally described in Supplement to Diagnostic Imaging, May 1995, Advanced Ultrasound, Editor: Peter L. OGLE, Editorial Offices: 600 Harrison St. San Francisco, Calif. 94107 USA.
Glass syringes and plastic syringes are described extensively in the publication by Junga (M. JUNGA (1973) Pharm. Ind. Vol. 35, No. IIa, pages 824 to 829). A mixture of glass and plastic is described in PCT Publication No. WO 96/00098.
Injectors are generally described in EP Publication No. 0 584 531.
The present invention provides apparatuses and methods for maintaining the homogeneity and integrity of an ultrasound contrast agent over a relatively long period of time without destroying the consistency of the ultrasound contrast agent and hence impairing its pharmacological and diagnostic properties. The dissociation begins immediately after the initial preparation of the ultrasound contrast agent, and at the latest after the syringe has been inserted into the injector when the latter is at rest (i.e., is not moving). By maintaining the homogeneity and integrity of the particles suspended in the contrast agent at optimal levels, the diagnostic properties of the contrast agent can be optimized.
The present invention further provides apparatuses and methods for continuous, controlled and/or reproducible agitation procedures for contrast agents. These procedures can be utilized between the time of preparation of the contrast agents and their injection into a patient.
Further, the present invention provides agitation procedures that can be specifically designed and/or adjusted for specific contrast agents, including ultrasound contrast agents.
Also, the agitation procedures may be designed to minimize turbulent agitation of the contrast agents, thereby reducing shear forces and other stresses that could be harmful to the integrity of the particles suspended in the contrast agents.
Moreover, the present invention provides a controlled application of magnetic energy to maintain the homogeneity of the contrast agent suspension, without mixing or otherwise destroying the particles of the contrast agents.
One aspect of the present invention is achieved by means of a syringe which is filled with ultrasound contrast agent for administering the contents thereof by means of an injector, wherein at least one ferromagnetic or magnetic agitation element is arranged in the syringe. The agitation element can be exposed to a magnetic field, the source of which is arranged in the syringe, on the syringe, around the syringe in the injector or associated with an accessory for the injector, and which is movable with respect to the syringe.
Another aspect of the present invention is achieved by means of an injector or an accessory associated with an Injector, which induces or is able to induce a magnetic field that acts on at least one ferromagnetic or magnetic agitation element in the syringe. The source of the magnetic field may be arranged in the syringe, on the syringe, around the syringe, in the injector or the accessory associated therewith. Further, the direction of the lines of flux in the magnetic field may be variable with respect to the syringe.
In one embodiment, the injector accommodates the syringes which are filled with an ultrasound contrast agent via at least one holder.
In a preferred embodiment, the present invention provides a combination of a syringe filled with a contrast agent and an injector or an accessory for use with an injector. At least one ferromagnetic or magnetic agitation element is contained in the syringe and is exposed to a magnetic field, the source of which is arranged in the syringe, on the syringe, around the syringe or in the injector or an accessory associated therewith. Further, the direction of the lines of flux of the magnetic field may be three-dimensionally variable with respect to the syringe.
In another embodiment, the injector may be connected to the syringe or the injector accessory may be connected to the syringe via the injector.
In another preferred embodiment, the syringes are made from plastic, glass or a plastic/glass material. Further, the syringes may be disposable syringes.
Moreover, the agitation element may be exposed to the magnetic field via a magnetic field coupling.